Originally posted by Erd§ I only mentioned this because AF can behave differently in low light situations.
That last one's quite evocative. Almost expect Jack the Ripper to emerge from the shadows...
+1... The best to get some reproducible results is to work in good condition: so lot of light, a good target on a single plane...
Once you have something that is set correctly you can compare with AF in LV and apply correction to get same focusing for both.
Be aware through that FF/BF might be dependant of focus distance and also that your AF point is not a point the size of the red dot you see but a cross the size of the "()" in your view finder too...